This invention relates to a sash window arrangement and particularly to a construction of sash window including frame profiles and a sealed window unit which has a simplified construction in relation to the sealing material which prevents air and moisture penetration between the profile and the outer edge of the window unit.
Conventionally a sealed window unit comprises at least two panes of glass which are separated by a spacer including a desiccant material. The spacer is suitably sealed to the inner faces of the glass sheets and then the outer edge of the window unit is completed by a tape or similar material. In this way penetration of moisture or air into the space between the glass sheets is prevented. The window unit is then seated into four separate lengths of frame profile which are connected into a rectangular frame surrounding the window unit. In many cases the profile includes a channel with a transverse web contacting the outer edge of the window unit and a pair of upstanding sides which confine the window unit.
Between the profile and the window unit it is necessary to provide a suitable bedding and sealing material so that the window unit is generally relatively loose fit within the profile and the space between the window unit and the profile is filled by rubber gaskets or other sealing material which is provided on the inner surface of the sides of the profile and generally projects upwardly beyond the top of the sides onto the face of the glass. In some cases this is provided by a separate gasket. In other cases it is provided by a bead of a sealant material. In all cases it is considered necessary to prevent the entry of air or moisture between the top edge of the side and the outer face of the glass sheet. This leaves an outer portion of the sealant material which is exposed to the environment and accordingly can crack and deteriorate.